With the continuous development of the transport network, the network topology is more and more complex, and the traffic becomes larger and larger. In order to satisfy the requirements of different service scheduling granularities, the Automatic Switch Optical Network (ASON) network supports various switching capabilities and service scheduling in different speeds under each switching capability. The supports for various switching capabilities and different speeds under each switching capability compose the multilayer network, e.g. the Multi-Protocol Label Switching (MPLS) and the Generalized Multiprotocol Label Switching (GMPLS) multilayer networks.
One Label Switched Path (LSP) is set up in the border node of the layer, and if this LSP is taken as a Traffic Engineering (TE) link of the upper layer to carry out the flooding, this LSP is called as a FA LSP, and this TE link is called as a Forwarding Adjacency (FA). A routing adjacency relationship does not exist between endpoints of the FA, but a signaling adjacency relationship exists.
The FA LSP can be set up automatically, and also can be set up manually.
The way of setting up the FA LSP manually is making a plan and configuration in advance. The greatest shortcoming of this way is not flexible sufficiently, or is unable to achieve the optimal resource utilization efficiency of the whole network.
The way of setting up the FA LSP automatically can adopt three ways of the Path Compute Element-Virtual Network Topology Manager (PCE-VNTM) coordination model, the Network Manager System-Virtual Network Topology Manager (NMS-VNTM) coordination model or the upper layer signaling triggered module. Both of the former two ways introduce the VNTM. However, the introduction of the VNTM will bring a layout difficulty, increase contents which requires coordinating and interacting, and increase connection setup time and instability.
When the upper layer signaling triggered module is adopted, the FA LSP is adopted as an upper layer TE link, and the FA attributes which can be inherited by the upper layer TE link include the interface switching capability, the TE link cost, the maximal LSP bandwidth of each priority, the unused bandwidth of all the priorities, the maximal reserved bandwidth, the protection attribute, the minimal LSP bandwidth (depending on the switching capability) and the Shared Risk Link Group (SRLG) and so on.
The interface switching capability of the FA inherits the interface switching capability of the nearest endpoint to the TE link composing the FA, and once the FA LSP is set up, the maximal LSP bandwidth of each priority, the unused bandwidth of all the priorities, the maximal reserved bandwidth and the minimal LSP bandwidth can be inherited. These attributes of the FA do not require constructing and obtaining according to corresponding attributes of each link on the FA LSP.
However, at present, there is not a corresponding scheme about how to inherit the TE link cost of the FA, the protection attribute, and the Shared Risk Link Group attribute and so on yet.